Cartridging of gelatinous and semigelatinous blasting explosives



.V. H. WILLIAMS March 1s, 1941.

CARTRIDGING OF GELATINOUS AND SEMIGELATINOUS BLSTING EXFLOSIVES Filed April 2,8, 1958 2 Sheets-Sheet l Vr'non /zarcourz Wz/amf mVENToR.

A TT ORNEY March 18, 1941- v. H. WILLIAMS 2,235,059

CRTRFDGING OF GELATIANOUS AND SEMIGELATINOUS BLASTING EXPLOSIVES Filed April 28, .1938 2 Sheets-Sheet 2 Vrzzozz Harcouri WzY/zmf INVENroR.

A TTORNEY- Patented Mar. 18, 1941 CARTRIDGING-OF GELATINOUS AND SEMI- GELATINOUS BLASTING EXPLOSIVES Vernon Harcourt Williams, Ardrossan, Scotland,

assignor to Imperial Chemical Industries Limited, a corporation of Great Britain Application April 28, 1938, Serial No. 204,890 In Great Britain May 3, 1937 8 Claims.

This invention relates to a method of cartridging gelatinous and semigelatinous blasting explosives, and to apparatus therefor.

The usual method of cartridging plastic explosives consists in extruding them through a coned nozzle, the diameter of which corresponds at least approximately to the desired diameter of the cartridge required; the extrusion being carried out either continuously, so as to form a sausage that is subsequently cut into the required lengths, or intermittently in single cartridge lengths. In general, the less plastic (i. e. permanently deformable under slight shear stress) the explosive, and the smaller the diameter of the extrusion nozzle, the more difcult it is to extrude the explosive in the above manner. Another cause of diiilculty in extrusion is internal friction between particles of suspended solids such as the salts commonly included in gelatinous and semigelatinous explosive compositions. Furthermore, changes in temperature in the crystal form of the salts, and similar effects may lead to changes in the consistency of the explosive sufficient to derange the operation of -the extrusion machine.

In practice, gelatinous and semigelatnous blasting explosives' are cartridged in a limited number of useful diameters by extrusion machines of appropriate nozzle diameters. Explosives of this type are known which have satisfactory explosive properties, but whose consistency renders them unsuitable for extrusion in the desired diameters. Although alternative methods of handling such explosives have been proposed, their manufacture has been generally avoided; and the development of such explosives has consequently been neglected.

Throughout the rest of this specication and the claims such explosives will be referred to generally, but not exclusively, as gelatinous exploslves.

This invention has as an ob-ject to devise methods and apparatus whereby a gelatinous explosive may be obtained in the desired dimensions for introduction into a cartridge case. Afurther object is to devise methods and apparatus whereby cartridge cases can be charged with a gelatinous explosive. Further objects will appear hereinafter.

These objects are accomplished by the following invention.

I have found that I `can obtain a-gelatinous explosive in the desired dimensions if a mass of gelatinous explosive confined in a cell bounded by rigid walls is divided into a number of cardischarging the separate cartridge lengths from 1G the tubes. v

The invention is illustrated by the drawings, in which:

Figure 1 represents a sectional elevation of a cell isolating a portion of a block of explosive with the battery of cutting tubes and template in cutting position;

Figure 2 represents a plan view of the template;

Figure 3 represents a sectional elevation of a portion of an 'apparatus constituting one form of the invention;

Figure 4 is an end view of a portion of this apparatus;

Figure 5 is a. side view of the cleaning piston disposed in the cutting cell.

In Figure 1 the strongmetal cell I of square 4section has been pressed into a. slab of a gelatinous explosive 5 and ultimately its bottom edge will abut against a removable slide l on which the explosive rests. The remaining wall of the cell consists of a stiff libre-board template 3 pierced with a number of holes to accommodate the corresponding number of tubes 2 each of diameter ofY about 1" held in a frame l0 with a clearance of about 11g" all round. The length of the wall of the cell I measured from the template 3 is the same as the thickness of the slab 5. The tubes 2 are made of thin brass and have sharp edges. The downward motion of the frame l0 holding the tubes 2 causes them to cut into the mass of explosive. When the tubes have been pressed in so as to abut against the removable slide 4, which is made of bre, wood, orthe like relatively soft material, the latter is Withdrawn laterally or given a small lateral motion to release the explosive adhering to it and the battery of cutting tubes is then withdrawn through the template, leaving the waste explosive in the cutting cell. The battery of tubes is then brought to a position, not shown in Figuresl 1 and 2, where the tubes are held over a corresponding battery of ready-made cases arranged vertically with the open ends upwards, and the tubesare lowered into the cases. A battery of pistons compresses the explosive from the tubes into the cases as the tubes are gradually withdrawn from the cases, and finally,

by the application of further pressure bythe pistons if required, the masses of explosive are caused to extend to the full diameter of the cases. The open ends of the cases are then folded in and crimped down. The mass of explosive remaining within the cell I is removed from it by detaching the template and pressing out the waste explosive by means of a wooden piston I8 of slightly smaller dimensions than the cutting cell; whereupon the template is replaced.

Referring to Figure 3, a sheet of gelatinous explosive 5 of predetermined size is fed from an intermittently travelling belt 1 into the cutting cell I; the required length of explosive is cut off, before introduction into the cell, by means of a stout Wooden cutter 8 which is arranged to travel with the explosive by mechanism (not shown) and is then forced by the action of the blade into the cutting cell. This cutter thereafter sforms a rigid back to the cell while the battery of cutting tubes 2 is moved through the removable template 3 to cut into the explosive. The template 3 has a limited travel on the walls of the cell I corresponding to the volume of the metal of the cutting tubes 2. After the cutting operation is complete the knife 8 is removed upwards to prevent adhesion thereto of the cut sections of explosive and the battery of tubes 2 is removed by mechanism `(not shown) acting on the frame III in which the tubes are secured, the mass of explosive lying between the tubes being held back by means of the removable template which is thereafter removed by mechanism (not shown) acting through the rods I I. The cell I is carried at the end of an arm I2 rotatable about an axis I3 while at the end of another arm I4 of the same length rotatable about the same axis there is a case holder I5 which has meanwhile been filled by mechanism (not shown) with paper cases open at one end, and the case holder is now rotated into the position previously occupied by the cutting cell so that the open ends of the cases I6 are opposite the cutting tubes containing the explosive. The frame I to which the tubes are attached is then moved forward and a battery of tamping pistons I1 is brought forward into 'contactwith the explosive in the tubes and the tubes are then gradually withdrawn so that the explosive is lpressed from the tubes into the cases. Further pressure is then applied by the tamping pistons so that the explosive sections are pressed and expanded so as to fill the cross-section of the case, the size of the cases after compressing the explosive being such that it fills them to a distancejust sufficient to enable the open ends to be folded and closed by crimping and the tubes to be removed- The folding and crimping mechanism are not shown in the drawings, but' the cases are brought by further rotation of the arm about the axis I3 to a fresh position opposite mechanism for the purpose.

At this stage the cutting cell I has reached a position not shown in the drawings where it is cleared of the waste explosive by passage through it forwards and backwards of a piston of solid section. After crimping has been completed and the cartridges have been removed and the cell cleaned out, further rotation about the axis I3 brings the case holder I5 back to the refilling position and the cutting cell I back to the position for re-engagement with the movable template, which is moved forward ready for the reloading operations.

Figure 4 shows in plan the arms I2 and Il rotatable about the axis I3 carrying at the ends the cutting cell I and the case holder I respectively in the positions in which the block of explosive cut off by the knife 8 is inserted into the cutting cell and the position in which the cases I6 are placed in the case holder. These arms are set at an angle of 90, and a rotation of 90 in the direction of the arrows brings the case holder I5 into the position in which the explosive is forced into tubes 2, and a further rotation through 90 in the same direction brings the cutting cell into position for removing the waste by means of a piston, while it also brings the case holder I5 into folding and crimping position.

In putting the invention into effect, the explosive may be conned in a cell formed by rigid and preferably fixed boundary walls defining a cross-sectional area many times larger than that of the cross-section of the individual cartridges required. The cell is provided in the third dimension with a removable wall and, on the opposite side, a displaceable battery of empty, open, rigid, thin-walled, parallel tubes. The removable wall enables the mass of explosive to be fed into and confined in the working space, and the battery of tubes is subsequently caused to cut into and through the mass of explosive to the said removably fixed wall. Substantially the 'only outlet for the explosive is into the battery of tubes; if the battery leaves any substantial free space whereby the explosive can readily find an alternative exit, there is provided a template which leaves only narrow apertures once the said battery has passed through it.

The battery of tubes may be connected together at their bases, having their lengths free to penetrate into the cell; or the tubes may have longitudinal connecting webs which may themselves penetrate into the explosive provided they do not merge the exterior walls of the tubes into massive columns, having a substantial cross-section exerting pressure on the explosive when the battery is forced into the cell.

The tubes comprising the batterly may be of circular, or oval, square, triangular, regular hexagonal or other cross-section, and it will be understood that it is only in special cases such as that of the cutting of cartridges of square, regular hexagonal, or triangular section that it is possible to dispense with the use of a template vf-cetween the tubes, or restrict it to an area aro ed. riphery of the battery. In the case of cylindrice tubes, the circular holes in the template are of only slightly greater cross-section than the external cross-section of the tubes, and the template is fixed in position so that it is not freely displaced by the mass of the explosive when the battery of tubes is passed through it, an object of the provision of the template being that the narrow'clearance left when the battery of tubes has been passed through it should impose so great a resistance to the Welling-over of the explosive that substantially the whole embedded length of any tube which cuts into the explosive becomes filled with it. In order to allow for the volume of the material of the tubes, the template may, however, be allowed a limited travel during the cutting operation.

'I'he adhesion of the explosive left' at the end movement imparted to the battery of tubes or the removable wall or both, or by a lateral movement imparted to the removable wall and it is conveniently effected by the same motion which is used to withdraw the wall into the position permitting the recharging of the cell.

The battery of tubes withdrawn from the cell and containing the lengths of explosive is brought to a position whereby relative movement between the battery of tubes and a battery of pistons registering within the tubes forces out the explosive, if desired into cases Ipreviously formed and positioned to receive the cartridge. Instead of abattery of pistons, compressed air or the like ma'y be employed, depending upon the readiness with which the material can be forced out.

In refilling the cell with the explosive it is sometimes possible to employ a press, since the difficulties of the extrusion of gelatinous explosive materials are dependent on the cross-section to which it is desired to reduce the material, and

the cell can be made of any conveniently large lcross-section. The battery may consist for instance of 20 or more tubes each of the approximate internal cross-section of the desired cord of explosive. A scraper may conveniently be passed over the outer face of the template, or the end of the face of the explosive as the case may be, after the cell has been refilled and before the battery of tubes advances to it for the next cutting operation.

When the explosive is expelled from the tube a slight expansion may occur owing to its gelatinous properties, and thus the cross-section of the explosive cord may be slightly greater than that of the tube. The cord, however, is substantially of the same cross-section throughout the main part of its length and is of approximately the length corresponding to the depth to which the battery of tubes has penetrated the' explosive, which is not the case if a block of gelatinous explosiveis cut by a tube of small cross section while the surface rof the block is allowed to well up freely.

This invention' is a valuable advance in the art, as it now makes it a practical proposition to use these gelatinous explosives, which have advantages for many purposes, in cartridges, without running the risks which were previously attendant on loading the cartridges.

As many apparently widely diierent embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to the specific embodiments thereof except as delined in the appended claims.

I claim:

1. Apparatus for the production of cartridge lengths of gelatinous explosive, which comprises a framework dening a cell adapted to be filled with gelatinous explosive, closed on all sides, except two opposing sides, by walls xed with respect to each other; and having on oneof the two opposing sides a movable wall, and having on the other opposing side at least one tubular cutter adapted to be forced through said framework until it impinges on the movable wall, and a template adapted to prevent extrusion of the explosive from said framework under the pressure of'said tubular cutter.

2. Apparatus for the production of cartridge lengths of gelatinous explosive, which comprises a framework defining a cell adapted to be filled with gelatinous explosive, closed on all sides, ex-

cept two opposing sides, by walls fixed with respect to each other; kand having on one of the two opposing sides a inovable wall, and having on the other opposing side at least one tubular cutter adapted to be forced through said framework until it impinges on the movable wall, and

means whereby said tubular cutter when charged with explosive is adapted to be separated from any residual explosive in said framework, and carried to a position from which the explosive in said tubular cutter can be discharged intoa cartridge case. i

3. Apparatus for the production of cartridge lengths of gelatinous explosive, which comprises a framework defining a cell adapted to be filled with gelatinous explosiveo closed on all sides, except two opposing sides, by walls fixed with respect to each other; and having on one of the two opposing sides a movable wall, and having on the other opposing side at least one tubular cutter adapted to be forced through said framework until'it impinges on the movable wall, means whereby said tubular cutter when charged with explosive is adapted to be separated from any residual explosive in said framework, and carried to a position from which the explosive in said tubular cutter can be discharged into a cartridge case, and at least one -plunger adapted to pass through said'tubular cutter impelling the explosive into said cartridge case.

4. Apparatus for the production of cartridge lengths of gelatinous explosive, which comprises a framework defining a cell adapted to be iilled with gelatinous explosive, closed on all sides, except two opposing sides, by `walls fixed with respect to each other; and having on one of the vtwo opposing sides a movable wall, and having Vby rigid walls,` except on two opposing sides,

means being provided'on one of such sides whereby the explosive can be fitted into the cell, further means being provided on the same side whereby a cutter can cut off a quantity of explosive suiilcient to :lill the cell, the said cutter being adapted to close this side of the cell, and means being provided on the opposite side of the cell whereby the battery of tubular cutters can be forced through the explosive in the cell, and withdrawn therefrom, charged with explosive, further means being provided whereby a battery of plungers can be passed through the said tubular cutters, the said battery of cartridge cases being so placed that by a rotation of the table it cornes into alignment with the tubular cutters, so that the passage of the plungers through the cutters causes the vcontents of the cutter to be forced into the cartridge cases, and means including a second plunger provided at another working position, whereby said plunger can be passed through the said cell to remove any explosive contained therein.

6. Apparatus comprising a rotatable table adapted to bring into a succession of working positions at least one cell and at least one battery of cartridge cases, the said cell being closed by rigid walls, except on two opposing sides, means being provided on one of such sides whereby the explosive can be fitted into the cell, further means being provided on the same side whereby a cutter can cut on' a quantity of explosive sum- -cient to flll the cell, the said cutter being adapted to close this side of the cell, and means being provided on the opposite side of the cell whereby the battery of tubular cutters can be forced .through the explosive in the cell, and withdrawn therefrom, charged with explosive, further means being provided whereby a battery of plungers can be passed through the said tubular cutters, the said battery of cartridge cases being so placed that by a rotation of the table it comes into alignment withthe tubular cutters, so that the passage of the plungers through the cutters causes the contents of the cutter to be forced into the cartridge cases, and means provided on that side of said cell from which said tubular cutters approach, whereby extrusion of the explosive under the pressure of the battery of cutters is prevented.

7. Apparatus for the production of cartridge lengths of gelatinous explosive, which comprises a framework of rigid walls defining a cell, said walls being i'lxed with respect to each other and closing said cell on all sides except two opposing sides, a movable wall disposed on one of the said two opposing sides, `a perforated template on the other opposing side, and at least one tubular cutter aligned with said template and adapted to .be forced through said cell to impinge on said movable wail.

8. Apparatus comprising a rotatable table adapted to bring into a succession of working positions at least one cutting framework defining a cell and at least one battery of cartridge cases, said cutting framework comprising rigid walls xed with respect to each other except on two opposing sides, means disposed cri one of said sides for introducing a block of explosive into the cell defined by said framework, and including a cutter for severing a quantity of explosive sufcient to flll said cell, said cutter being adapted to close the adjacent side of said framework, means provided on the opposite side of said cell including a battery of tubular cutters adapted to be forced through the explosive in the cell defined by said framework and withdrawn therefrom charged with severed explosive, means including a battery of plungers adapted to be passed through said tubular cutters, the said battery of cartridge cases being disposed so that by rotation of the table it comes into alignment with said tubular cutters permitting the contents of each cutter to be forced into a corresponding cartridge case upon the passage of said plungers through said cutters.

VERNON HARCOURT WILLIAMS. 

